Yugoslavia's biggest underground airport lies in ruins.

A musical instrument played by the sea.

An ethereal glowing blue ocean cave in Croatia.

A wonderful museum dedicated to the local straw hat industry.

An unmistakable facial pareidolia in the Julian Alps also includes a fantastic tale.

Strange rumors surround the artist who created these solemn metal guard dogs.

A crumbling World War I fort that is reached through a series of concrete tunnels.

The walls of this medieval church are covered with perfectly preserved frescos, including a pristine example of the Dance of Death.

Martin Bricelj Baraga's monolithic sculpture measures the blueness of the sky, and changes color to match it.

This massive subterranean fissure is known as the "underground Grand Canyon."

A kindergarten shaped like a cat with a tail that's a slide.

This abandoned mansion has a window for every day of the year, and is a temple for ghost hunters.

Bold black and white motifs of life and death add a dramatic flair to this 17th-century crypt.

At first glance, this area seems like just another city park, but the lush landscape hides a dark past.

There are thousands of tributes and memorials to the King, but none quite like this one in a Kraków city park.

Poland's oldest surviving university building holds a wealth of historic science instruments including some used by Copernicus.

Real bones which are said to have belonged to a Polish dragon.

Norway's oldest cathedral still in use.

The world's largest moose statue towers above the highway between Oslo and Trondheim.

Mound of stones marking the burial site of the world's most famous orca.

Thousands of years of crashing waves gave this mushroom-shaped rock its svelte figure.

An intricately carved Viking church overlooks a glistening fjord.

A thin pane of glass keeps visitors from sliding off this futuristic skywalk.

A Viking-style brewpub named for a Norse sea giant, in the heart of fjord country.